power adapter polarity (+ or -)?

I just purchased a 2GB clip and got a Phillips CD and MP3 adapter which will play through my car stereo and it also came with a charger. Before connecting, the instructions say to make sure that you know what the polarity of the equipment is that you intend to power…either negative (-) or positive (+).  There is no indication anywhere of what the clip is (does it just apply to CD players??). I’m new at this and don’t want to cook the thing before I’ve had a chance to enjoy it! Thanks in advance for any help given!

USB doesn’t have adjustable polarity in the sense that you’d want to mess with it. Just use a mini-USB A cable like the one supplied with your unit to charge it. You’ll need a USB power adapter for your car so you can plug said cable into said adapter.